How do you determine what bass tabs should accompany certain acoustic chords.

Ok, i am not really new to bass, but i am new to playing support. My friends asked me to play with him and his friends for a gig, but he wants me to play support. I can play some key notes, but it doesn't sound right sometimes, is there a specific way to find out what i should be playing.

Just because the notes are from the key they still might not be the right notes for the current chord. Basic theory know your chord tones they are your skeleton of choices. But if real unsure of what's going on roots and 5ths have be the foundation for bass since time began.

RED ALERT !!!

IT'S THE TAB ATTACK